1. Field of the Invention
The invention set forth in this specification pertains to new and improved flexible couplings and, more particularly, to such couplings employing an elastomeric belt and operating in a horizontal shear mode.
2. Description of Related Art
Flexible couplings have long been used for transmitting rotation from one shaft to another. Such couplings are normally used in order to accommodate comparatively minor shaft alignment problems such as are occasionally encountered because of manufacturing or assembly errors. Because of the fact that these devices are widely used and have been known and used for many years, many different types of flexible couplings have been proposed, built, and used.
One prior art coupling device includes two hubs or hub elements, each adapted to be connected to a respective one of a pair of generally axially aligned shafts. Each hub is provided with a like number of extending lugs, teeth, fingers, or ribs equally spaced around its periphery. Teeth are of a length such that the hubs can be mounted on their respective shafts with each tooth of the first hub aligned with and slightly spaced apart horizontally from a corresponding tooth of the second hub. The spaces between pairs of opposed teeth are then occupied by corresponding projections on a belt-like motion transmitting means in order to cause the hubs to rotate in synchronism as one of the shafts is rotated. The belts used in these prior art couplings have been flexible, somewhat resilient or elastomeric belts or bands capable of being wrapped around the hubs so that the projections on them engage the teeth on the hubs.
Such couplings operate in what is termed a "vertical shear" mode. This means that the force tending to shear the flexible band or belt has a vertical component, i.e., a component perpendicular to the axis of rotation of the shafts, i.e., the horizontal axis. If overtorqued, the mean and/or vibratory torque will cause a twist angle between the driving and driven hubs, causing an undesirable axial thrust load on the bearings and/or any other rotating parts. Consequently, the longevity of the rotational equipment is impaired.
While the prior art couplings have the drawback of occasioning unwanted wear on machinery, they exhibit several advantages. The elastomeric motion transmitting means or belt provides misalignment capacity and transmits power uniformly. It will fail in severe overloading, protecting the rotational equipment from damage. The elastomeric insert also provides damping, which protects equipment from vibratory strain causing loss of longevity. The coupling design also permits ease of assembly and replacement of inserts.